I have plans for a Southern Rilfe circa 1760 or so that had a square breech barrel, obviously a fowler or musket lock and other spare parts and or parts from destroyed firearms. No nose cap or buttplate. Mostly I like to try to build a what likely could have been and favor early guns such that a trigger guard from an 1840 Bedford county would look rather silly on a gun intended to represent something from about 1770. However, more and more I tend to like the plainer working guns. By their nature of being a "barn" gun I doubt that a very high proportion of shimmels have survived.
Northmn